Core performance analyses are conducted for fast reactors that accept and recycle the plutonium and minor actinides (MAs) recovered from light water reactor (LWR) spent fuel, together with the plutonium and MAs from the fast reactors’ own production. Metal, nitride, and oxide are the fuel materials used to compare the neutronic and safety parameters and to discuss acceptable minor actinide content. Based on the material balance of the analyzed cores, an LWR-fast reactor fuel cycle model is used to calculate the mass flow of the plutonium and MAs and to estimate their total amount in the waste stream.